Field of the Invention
This invention relates to electric discharge lamps and has particular reference to an improved fluorescent lamp of compact size and high brightness that is suitable for use in residential and commercial lighting fixtures.
Description of the Prior Art
Electric discharge lamps having envelopes which are internally partitioned to provide one or more elongated discharge paths are generally well known in the art. U.S. Pat. No. 2,121,333 issued June 21, 1938 to Barclay discloses such a lamp of single-ended construction having glass panels that are joined to the glass envelope and serve as the partition means. Another type of single-ended fluorescent lamp is disclosed in U.S. Pat. No. 3,024,383 issued Mar. 6, 1962 to Doering wherein a thin sheet of glass or ceramic, or a stiffened sheet of fiberglass or the like, is used as the partition means. The partition is supported by the sealed end portion of the glass stem or by a disc-like base member that can be grooved to accept the partition and is seated on the stem. The partition assembly consists of a single panel or two panels that partly intersect and are perpendicular to one another. Short-circuiting of the discharge is prevented by thickening the edges and/or elastically seating the edges of a glass-textile or fiberglass partition against the envelope walls, or by providing the edges of a rigid partition with a compressible or elastic border or lining of fiberglass. The partition and inner surface of the envelope are coated with a fluorescent material. The fluorescent coating on the partition can, if desired, be replaced by a coating of ultraviolet reflective material such as magnesium oxide, silica powder, etc.
Fluorescent lamps having partitions that are fabricated from sheet metal which is coated with phosphor are also known in the art and are disclosed in U.S. Pat. Re. Nos. 22,896 (issued July 8, 1947 to Polevitzky) and 3,508,103 issued Apr. 21, 1970 to Young. A single-ended fluorescent lamp which contains a concentric cylindrical glass partition and several electrodes which are sequentially energized in such a manner that the discharge passes through the cylindrical partition and sweeps around the annular chamber defined by the partition and the envelope is disclosed in U.S. Pat. No. 3,609,436 issued Sept. 28, 1971 to Campbell. An electric discharge lamp of single-ended construction having an envelope that contains a box-like arc-enclosure consisting of joined metal baffles and light transmitting side panels that are secured to a stem component and define a tortuous path for the discharge is disclosed in U.S. Pat. No. 2,030,715 issued Feb. 11, 1936 to Pirani et al.